The project is directed toward definition of the role of cerebral cortical integration in motor function. It takes advantage of recent anatomical investigations of cortico-cortical connections which allow for parcellation of the cortical grey mantle on the basis of intracortical projections (as opposed to the more traditional parcellations based on cytoarchitecture or thalamocortical projections). It utilizes one hemisphere as a control for the other, taking advantage of the lack of hemispheric dominance in the monkey, and split brain preparations. A long lasting defect in learned motor tasks, but not in power or spontaneous motor performance was found following bilateral lesions in a frontal region of polysensory convergence cortex (FPC- Delinated by its intrahemispheric cortical connections, it comprises Brodmann's area 8 as well as parts of areas 6 and 9). The studies test possible explanations for this loss: (1) it is a cortical integration defect (i.e., apraxia) and will appear worse in all acquired motor tasks performed by a hand controlled from a motor cortex which has been isolated (by ipsilateral subpial resection and telencephalic commissure splitting) from FPC input; (2) it is a simple motor defect created by lesioning of the primary representation of the axial musculature, with its rich interhemispheric connections in the most caudal reaches of the FPC region. As such the loss should be worse in all gross motor tasks in animals with unilateral lesions of posterior area 6--anterior area 4, and splits; (3) the loss is not primarily dependent upon neocortical integrational or representational mechanisms and will be found following stereotaxically placed subcortical lesions in all motor tasks. It is anticipated that the results of these studies will be helpful in the analysis of frontal apraxias exhibited by human beings.